1. Technical Field
The present disclosure relates to a touch detection device capable of detecting an external contiguous object, a touch detecting display device with a touch detecting function provided with the same, and an electronic apparatus.
2. Description of the Related Art
Recently widely known is a display device with a touch detecting function including a touch detection device that detects a contiguity operation of an external contiguous object, such as a finger and a stylus pen. Such display device with a touch detecting function is called a touch panel. There have been developed a touch panel provided with a touch detecting unit on a display device, such as a liquid-crystal display device, and a touch panel provided with a touch detecting unit integrated with a display device, such as a liquid-crystal display device.
Some types of detection methods of touch detection devices are known, including optical detection type, resistive detection type, and capacitive detection type, for example. The capacitive touch detection device can be formed in a relatively simple structure and driven with low power consumption. The display device with a touch detecting function including such a touch detection device displays various types of button images and the like. A user performs a contiguity operation with an external contiguous object on the display device, thereby performing an input operation of desired information via a touch detecting unit in the same manner as in the case of typical mechanical buttons. Touch detection devices can be provided substantially integrally with display devices, unlike input devices, such as keyboards, mouses, and keypads, provided in a manner externally coupled to display devices. Thus, touch detection devices are provided to various types of electronic apparatuses, such as mobile phones, television receivers, digital cameras, and notebook personal computers.
In a capacitive touch detection device, a first wiring and a second wiring are laminated. The capacitive touch detection device applies a voltage to one of the wirings (a drive electrode) and detects a detection signal with the other of the wirings (a touch detection electrode) (refer to Japanese Patent Application Laid-open Publication No. 2012-43298 (JP-A-2012-43298)). In the capacitive touch detection device, the value of the signal detected in touch detection changes when an external contiguous object is in contiguous with a detection area in which touch detection is performed by the drive electrode and the touch detection electrode. Based on the change, the capacitive touch detection device detects contiguity of the external contiguous object. JP-A-2012-43298 also discloses a technology for causing the width of a pad at the end of the drive electrode to vary depending on the position.
In the touch detection device, a plurality of drive electrodes are arranged side by side in a predetermined direction (an array direction). In other words, the touch detection device is formed of the drive electrodes aligned in the array direction. To detect a touch, the touch detection device changes a drive electrode to which a voltage is applied by time division and detects a signal with the touch detection electrode at each detection timing. If a touch is being made in an area in which the drive electrode is arranged, the touch detection electrode overlapping with the drive electrode near the touch position detects a change in the signal. The touch detection device detects the touch position based on the change in the signal. The touch detection device performs interpolation of the touch position based on signals detected when a voltage is applied to adjacent drive electrodes, that is, signals detected at each position of the adjacent drive electrodes. Thus, the touch detection device detects the touch position at a higher resolution than the arrangement density of the drive electrodes.
In the touch detection device, a drive electrode positioned at an end in the array direction has no adjacent drive electrode arranged on one side thereof in the array direction. If a signal is detected at a detection timing when a voltage is applied to the drive electrode positioned at the end in the array direction, interpolation is performed on the signal only with a signal detected at a detection timing when a voltage is applied to an adjacent drive electrode arranged on the other side thereof in the array direction. This reduces the accuracy of the interpolation at the position compared with the other positions.
For the foregoing reasons, there is a need for a touch detection device that is capable of enhancing the detection accuracy of a touch, a display device with a touch detection function provided the same, and an electronic apparatus.